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Current-mode universal filter using current feedback amplifiershttp://nopr.niscair.res.in/handle/123456789/9594
Title: Current-mode universal filter using current feedback amplifiers
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<br/>Authors: Shah, N A; Rather, M F; Iqbal, S Z
<br/>
<br/>Abstract: A new current-mode (CM) universal filter based on and
employing three each of non-inverting current feedback amplifiers (CFAs),
capacitors, and resistors is presented. Without changing the circuit topology
the output currents simultaneously supports lowpass (LP), highpass (HP), and
bandpass (BP) responses. The notch (BR) and allpass (AP) filtering functions
can be achieved by connecting the appropriate nodes without requiring the use
of additional components. The proposed circuit enjoys low passive sensitivities
and orthogonal tuning of the parameters natural frequency<i style="">,</i><i style="">ω<sub>0</sub></i><sub> </sub>and
quality factor, <i style="">Q</i>. Personal
computer-simulation programme with integrated circuit emphasis (PSPICE)
simulated results agree well with calculated values.
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<br/>Page(s): 375-377Magnetic behaviour of nano-particles of Ni<sub>0.5</sub>Co<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub> prepared using two different routeshttp://nopr.niscair.res.in/handle/123456789/9593
Title: Magnetic behaviour of nano-particles of Ni<sub>0.5</sub>Co<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub> prepared using two different routes
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<br/>Authors: Chander, Subhash; Srivastava, Bipin K; Krishnamurthy, Anjali
<br/>
<br/>Abstract: Literature reports on bulk sample of the ferrite Ni<sub>0.5</sub>Co<sub>0.5</sub>Fe<sub>2</sub>O<sub>4</sub>
confirm a complete inverse spinel structure. On site occupancy and magnetic
anisotropy on nano-particle samples of the titled ferrite prepared using two
different routes – a wet chemical co-precipitation process and sol-gel method
have been studied. Estimated average particle sizes of the two samples
(referred to as NCWET and NCSOL) are ~75Å and ~190Å respectively. Small angle
neutron scattering measurements made on the fluid sample comprising the sample
prepared by wet chemical process gives median size ~77Å with standard deviation
σ = 0.60. Mössbauer studies at 300K show
that the two ferrite samples maintain inverse spinel structure even in
nano-crystalline state. Magnetization and Mössbauer measurements show that part
of the sample in both the cases is in superparamagnetic state. Magnetic
anisotropy is larger in the nano-particle state and surface spin disorder also
contributes to this.
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<br/>Page(s): 366-370Pressure-volume-temperature <i>(P-V-T) </i>relationship for NaCl crystalhttp://nopr.niscair.res.in/handle/123456789/9592
Title: Pressure-volume-temperature <i>(P-V-T) </i>relationship for NaCl crystal
<br/>
<br/>Authors: Joshi, D C; Gupta, A P; Singh, S
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<br/>Abstract: A method for determining the compression data (<i>V/V</i><sub>0</sub>)
at simultaneously elevated temperature and pressure up to a pressure of 35 kbar
and a temperature of 773K has been developed. This method is based on the
Chopelas Boehler approximation for variation of the Anderson-Gruneisen parameter
<img src='/image/spc_char/delta1.gif' border=0><sub>T</sub> with the change in
compression. The calculated values are found to be in good agreement with the
experimental data.
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<br/>Page(s): 347-350Four-level approximation in disordered mediumhttp://nopr.niscair.res.in/handle/123456789/9591
Title: Four-level approximation in disordered medium
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<br/>Authors: Sakwa, W T; Khanna, K M; Mueni, M; Rotich, S; Torongey, P K
<br/>
<br/>Abstract: The adsorption of superfluid <sup>4</sup>He into a disordered
medium, the disappearance of superfluidity due to adsorption, and the
subsequent appearance of superfluidity when more <sup>4</sup>He flows into the
disordered medium have been described by the four-level approximation. The
adsorption of superfluid <sup>4</sup>He into a disordered medium depletes the
ZMS as the particles shift to higher excited levels resulting in ‘four-level
approximation’. Superfluidity reappears on further adsorption but at a lower
temperature implying that the <i>T</i><sub>c </sub>value of a four-level system
should be lower than the <i>T</i><sub>c</sub> value for a three-level system,
which is in agreement with the experimental observations.
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<br/>Page(s): 355-360